1. Field of the Invention
The present invention relates generally to processes for producing and recovering 1,3-propanediol. More particularly, it concerns methods that rely on solvent extraction for production and recovery of 1,3-propanediol.
2. Description of Related Art
Purified 1,3-propanediol (PDO) can be produced commercially by methods known in the art that can involve fermentation, chemical, and mechanical separation processes. It is possible to produce 1,3-propanediol by fermentation, and production in this way requires methods of purifying 1,3-propanediol by targeting the removal of impurities that are the result of fermentation. When PDO is produced by fermentation the broth can contain a number of compounds such as glycerol and 1,2,4-butanetriol, which are very similar in chemical composition and properties to PDO. Glucose, a material that can be used to feed fermentation, is a compound that also has similarities to 1,3-propanediol, and residual amounts of glucose can remain after fermentation. A disadvantage of the fermentation route using glucose for the production of 1,3-propanediol is that sugars such as glucose will create color in downstream processes involving heat, such as distillation and evaporation. Preferably the residual glucose is separated from the PDO to purify the PDO. There is a need for a process to separate 1,3-propanediol from impurities in addition to sugars that will result in greater purity of the PDO, and that can eliminate or reduce the amount of energy intensive distillation (e.g., a common method of purifying PDO) required to produce the purified PDO.